If you're a gardener, you're aware that nematodes are "microscopic, eel-like roundworms" and that "most troublesome species in the garden are those that live and feed within plant roots most of their lives and those that live freely in the soil and feed on plant roots," according to the UC Integrated Pest Management Program website on nematodes.

If you attended the ninth annual UC Davis Biodiversity Museum Day, you learned hands-on information from nematologists Christopher Pagan and Corwin Parker, doctoral students who study with major professor Steve Nadler, professor and chair of the UC Davis Department of Entomology and Nematology.

Pagan and Parker held forth at their display in the Academic Surge Building, where they fielded questions about nematodes and showed specimens to the visitors. The nematode collection was one of 13 museums or collections featured at the Biodiversity Museum Day, always held the Saturday of Presidents' Weekend.

Many visitors asked what nematodes are, they related.

Other common questions asked:

Do I have nematode parasites?

How dangerous are nematode parasites/can they kill you?

How long do they live?

How many species ofode are there?

Are soil nematodes good or bad for my garden?

Parker shared some of the answers:

Do I have nematode parasites?

Probably not unless you've been traveling a lot. The most common nematode parasite of humans in the US is pinworm which most children get, but not adults. Worldwide however, hundreds of millions of people are infested with parasites including Ascaris, hookworm, and whipworm.

How dangerous are nematode parasites/can they kill you?

Nematode parasites are usually relatively benign unless you have a lot of them. Potentially fatal exceptions do exist, such as zoonotic infections of rat lungworm and raccoon roundworm, but those are rare.

How long do nematodes live?

It depends on the species and life history. Parasitic nematodes can live for a long time, while most free-living nematodes have relatively short lifespans. Some nematodes that live in harsh environments such as deserts can extend their lives by going into a state of suspended animation until environmental conditions are optimal.

How many species of nematode are there?

More than 30,000 described species, but it's estimated there are more than 1 million total.

Are soil nematodes good or bad for my garden?

Most soil nematodes are neutral to beneficial for your garden. They're an integral part of the soil ecosystem and help with nutrient cycling, and some kill of root-feeding insects. There are some plant-parasitic nematodes, but most don't cause significant damage.

The event, to take place from 9 a.m. to 4 p.m., is free and family friendly. All 13 sites are within walking distance except for the Häagen-Dazs Honey Bee Haven on Bee Biology Road and the Raptor Center on Old Davis Road.

The science-based event, always held the Saturday of Presidents' Day weekend, features the diversity of life. It is billed as a “free, educational event for the community where visitors get to meet and talk with UC Davis scientists from undergraduate students to staff to emeritus professors and see amazing objects and organisms from the world around us,” according to Biodiversity Museum Day coordinator Tabatha Yang, education and outreach coordinator for the Bohart Museum of Entomology. The schedule is online.

Last year's event drew more than 4000 visitors. Schedules vary from collection to collection.

New this year will be public talks from noon to 1 p.m. in 194 Young Hall. Speaking will be butterfly expert Art Shapiro, distinguished professor of evolution and ecology; Gabriella Nevitt, professor, Department of Neurobiology, Physiology and Behavior, College of Biological Sciences; and Melanie Truan, staff research associate, Museum of Wildlife and Fish Biology and former postdoctoral researcher at UC Davis. Titles will be announced.

All participating museums and collections have active education and outreach programs, Yang said, but the collections are not always accessible to the public. Maps, signs and guides will be available at all the collections, and also online at http://biodiversitymuseumday.edu, and on social media, including Facebook and Twitter, @BioDivDay.

Capsule information on each:

Arboretum and Public Garden, 9 a.m. to 1 p.m. Melissa Cruz Hernandez, outreach and leadership program manager, Arboretum and Public Garden, notes that the Arboretum activities will all be at the Shields Oak Grove, alongside the School of Veterinary Medicine, Garrod Drive. This is a change from last year. The Arboretum Ambassadors are planning fun-filled oak tree conservation activities the whole family will enjoy. “Learn about the many contributions oaks make to sustaining habitat biodiversity, what UC Davis and the Arboretum and Public Garden are doing to protect the trees, and win prizes for participating in the games at the Shields Oak Grove!”

Hernandez announced the following Arboretum activities:

GATEways Outreach Ecological group: Learn what it is like to live as an oak tree through a life size board game and win prizes! Explore the ecological impacts oaks have in our community and discover about how the changing climate is impacting this important species.

GATEways Outreach Humanities group: Did you know the US Constitution was signed in oak gall ink? Join us and try out oak gall ink for yourself, and engage in mindfulness activities.

Museum Education: Take a self-guide tour through our iconic oak grove and learn about the unique characteristics of 12 of our favorite trees.

Emily Griswold Tour: Join oak expert and Director of GATEways Horticulture, Emily Griswold, on an engaging tour of the oak grove. Uncover behind the scenes information about the grove and get your quercus questions answered.

Bohart Museum of Entomology, 9 a.m. to 1 p.m. The Bohart Museum of Entomology, located in Room 1124 of the Academic Surge Building on Crocker Lane, is the home of a global collection of nearly 8 million insect specimens. Insect scientists will meet with the public to help them explore insects and spiders (arachnids). Highlights will include the 500,000-specimen butterfly/moth collection, curated by entomologist Jeff Smith. The Bohart maintains a live “petting zoo,” comprised of Madagascar hissing cockroaches, walking sticks and tarantulas. Also, the UC Davis Library set up a Mary Foley Benson exhibit in the Academic Surge hallway. It will be up ponly for the month of February. "The library, is, of course full of special collections including very important research materials on bees and on nematodes," noted Tabatha Yang, the Bohart education and outreach coordinator.

California Raptor Center, 9 a.m. to 1 p.m. Visitors to the The California Raptor Center, located at 1340 Equine Lane, Davis, just off Old Davis Road, will see a living collection of non-releasable raptors. The center's educational ambassador birds will be out "on the glove," so visitors can get a close view of the birds of prey, and talk to the volunteers. Julie Cotton, volunteer and outreach coordinator, said visitors will see "on the glove" Swainson's hawks, a white-tailed kite, barn owl, great-horned owls and a eregrine falcon. Viewable in their exhibits will be golden eagles, American kestrels, turkey vultures, prairie falcon and Western screech owls.

Museum of Wildlife and Fish Biology, 9 a.m. to 1 p.m The Museum of Wildlife and Fish Biology, located in Room 1394 of the Academic Surge Building, Crocker Lane (off LaRue Road) will feature an action packed morning with displays highlighting carnivores, bats, reptiles and fish, said director Andrew Engilis Jr. Visitors will see specimen preparation demonstrations. Also planned is a kids' craft table.

Paleontology Collection, 9 a.m. to 1 p.m. Visitors at the Paleontology Collection, located in the Earth and Physical Sciences Building, 434 LaRue Road, can view fossil specimens dating from as old as 550 million years ago to more recent animal skeletons. Paleontology graduate students in invertebrate and vertebrate paleontology will answer questions and provide interesting factoids.

Phaff Yeast Culture Collection and Viticulture and Enology Culture Collection, 10 a.m. to 2 p.m.The Phaff Yeast Culture Collection in the Department of Food Science, and the Wine Yeast and Bacteria collection in the Department of Viticulture and Enology, are jointly hosting exhibits and tours. They are located at the Robert Mondavi Institute Teaching Winery and Brewery Building, 392 Old Davis Road, on campus. Visitors to the yeast collection exhibits can taste kombucha and Vegemite, smell lots of different species of yeast, look at yeast and bacteria cells under the microscope, learn about the history of yeast research at UC Davis, and hear about the latest discoveries coming out of the UC Davis yeast collections, says Kyria Boundy-Mills, curator of the Phaff Yeast Culture Collection, Food Science and Technology.

Anthropology Museum, noon to 4 p.m. Visitors to the Department of Anthropology Museum, located in 328 Young Hall, will see collections of archaeological, ethnographic, biological and archival materials. They will "experience our cultural diversity through art pieces from around the world, our complex evolutionary history through primate skeletons and fossil hominin casts, or how archaeologists at UC Davis work across the globe to understand past cultural diversity through the artifacts people leave behind," said Professor Christyann Darwent of the Department of Anthropology. "There will also be an opportunity for visitors to learn to make tools from obsidian stone and to throw a spear with an atlatl."

The Botanical Conservatory, 9 a.m. to 4 p.m. "We again expect our cacao tree to be loaded with ripe fruit for display amongst the plethora of plant we'll be displaying!" says collections manager Ernesto Sandoval. "We'll also be showcasing our very well established pond that made a splash last year and newly added small epiphyte tree along with three towering Titan Arums in leaf! if the outdoor weather is good, Visitors will be encouraged to take a walk over to the nearby Joe and Emma Lin Biological Orchard and Gardens and bask in the biodiversity of these sizable plots of Biodiversity and the neatly pruned fruit tree orchard." The Botanical Conservatory is located on Kleiber Hall Drive.

Häagen-Dazs Honey Bee Haven, noon to 4 p.m. Visitors to the Häagen-Dazs Honey Bee Haven, a half-acre bee demonstration garden located next to the Harry H. Laidlaw Jr. Honey Bee Research Facility, Bee Biology Road, can learn about bees and see the plants they frequent, said manager Christine Casey. Guests will learn how to identify bees. They can also use a bee vacuum to catch, observe and release bees. A six-foot long sculpture of a worker bee by artist Donna Billick of Davis anchors the haven.

Nematode Collection, noon to 4 p.m. The nematode collection will open from noon to 4 p.m. in the Science Laboratory Building, off Kleiber Hall Drive. It will feature both live and slide-mounted nematodes, as well as jars of larger parasites. Nematodes, also called worms, are described as “elongated cylindrical worms parasitic in animals or plants or free-living in soil or water. They exist in almost every known environment.”

Marine Invertebrate Collection, noon to 4 p.m. The Marine Invertebrate Collection in the Science Laboratory Building, off Kleiber Hall Drive, will have touch tanks, preserved specimens, and some displays showing aspects of marine ecology and evolution. There will also be a seashell activity for kids, said Ivana Li. "In our touch tanks, we'll likely have sea stars and sea urchins. We are showing all the different geographical locations from which they were collected. This means that people can match up where specimens like our slipper lobster or salp came from. Other displays that we will have are on how to distinguish true crabs from other animals, and a display on seaweed ecology."

The sponsors made it all possible to have this event free to the public, Yang said. Ink Monkey is providing 300 t-shirts for the volunteers, and Marrone Bio Innovations and Novozymes are also major supporters. Other supporters include the UC Davis Honey and Pollination Center, UC Davis Library, White Labs Inc., Margaret Berendsen, Fletchers Real Estate, Peter Lash and Dan Potter.

"Also, individuals can donate to the Biodiversity Museum Day cause by going to our link on our website. We set up a giving page through the College of Agricultural and Environmental Sciences."

In a recent publication in PLOS Genetics titled "Effector Gene Birth in Plant Parasitic Nematodes: Neofunctionalization of a Housekeeping Glutathione Synthetase Gene," Eves-van den Akker noted that "Plant parasitism has arisen four times independently within the phylum Nematoda, resulting in at least one parasite of every major food crop in the world. Some species within the most economically important order (Tylenchida) secrete proteins termed effectors into their host during infection to re-programme host development and immunity. The precise detail of how nematodes evolve new effectors is not clear."

He and his colleagues reconstructed the evolutionary history of a novel effector gene family. They showed that "during the evolution of plant parasitism in the Tylenchida, the housekeeping glutathione synthetase (GS) gene was extensively replicated. New GS paralogues acquired multiple dorsal gland promoter elements, altered spatial expression to the secretory dorsal gland, altered temporal expression to primarily parasitic stages, and gained a signal peptide for secretion. The gene products are delivered into the host plant cell during infection, giving rise to 'GS-like effectors.'"

"Our results demonstrate the re-purposing of an endogenous housekeeping gene to form a family of effectors with modified functions," Eves-van den Akker wrote. "We anticipate that our discovery will be a blueprint to understand the evolution of other plant-parasitic nematode effectors, and the foundation to uncover a novel enzymatic function."

Eves-van den Akker studied biology at the University of Leeds from 2007 to 2019. During his final year, in the lab of Professor P. E. Urwin, he became interested in plant-pathology, and "the fascinating and potentially useful abilities of plant-parasitic nematodes." From 2010 to 2014, he studied for a doctorate in plant-nematode “effectors,” jointly appointed between the University of Leeds and The James Hutton Institute.

In 2015, he was awarded a three-year Anniversary Future Leaders Fellowship from the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation, a non-departmental public body funded by a grant-in-aid from the UK government. His fellowship was designed to understand the structural and molecular detail of nematode effector function.

That led to a discovery that provided what he calls "the first tangible insight into the regulatory processes underlying plant-nematode parasitism," and that in turn, resulted in his five-year BBSRC David Phillips Fellowship in 2018. With this second fellowship, he established a research group at the University of Cambridge and was elected Fellow of King's College.

Community ecologist Rachel Vannette, assistant professor, is coordinating the winter quarter seminars, all held on Wednesdays at 4:10 p.m. in 122 Briggs Hall. The remaining schedule:

Coordinated by assistant professor and community ecologist Rachel Vannette, the seminars will take place at 4:10 p.m., every Wednesday in Room 122 of Briggs Hall except on Nov. 20 (no seminar due to the Entomological Society of America meeting in St. Louis, Mo).

The schedule:

Sept. 25James Nieh, professor, Section of Ecology, Behavior and Evolution, Department of Biological Sciences, UC San DiegoTopic: "Animal Information Warfare: How Sophisticated Communication May Arise from the Race to Find an Advantage in a Deadly Game Between Honey Bees and their Predators" (See lab website)Host: Brian Johnson, associate professor, Department of Entomology and Nematology

Oct. 16:Rebecca Irwin, professor, applied ecology, North Carolina State University, Raleigh, N.C.Topic: (to be announced; she specializes in the ecology and evolution of multiple-species interactions, pollination biology, and species invasions)Host: Rachel Vannette, assistant professor, Department of Entomology and Nematology

Oct. 23: Julián Hillyer, director of the program in career development and associate professor of biological sciences, Vanderbilt Institute for Infection, Immunology and Inflammation, Nashville, Tenn.Topic: "Not So Heartless: Functional Integration of the Immune and Circulatory Systems of Mosquitoes"Host: Olivia Winokur, graduate student, Chris Barker lab

The seminars are free and open to all interested persons. Some will be recorded for later viewing on YouTube. More information on the fall seminars or schedule is available from Vannette at rlvannette@ucdavis.edu.

If you read The Plant Journal today, you may have noticed the exciting research published on nematodes.

And it has a University of California, Davis, connection.

An international team of 10 scientists, led by plant nematologist Shahid Siddique, a former research group leader at the University of Bonn, Germany, and now an assistant professor in the UC Davis Department of Entomology and Nematology, has discovered the role of a plant's endodermal barrier system in defending against plant-parasitic nematodes.

“We discovered that the integrity of the endodermis—a specialized cell layer that surrounds the vascular system and helps regulate the flow of water, ions and minerals--is important to restrict nematode infection,” said Siddique, who joined the UC Davis faculty in March after serving several years at the University of Bonn.

“We found that having defects in endodermis make it easier for parasites to reach the vascular cylinder and establish their feeding site. Although, this finding is a result of basic research, it opens new avenues to for breeding resistance against cyst nematodes in crops.”

Siddique collaborated with scientists from Germany, Switzerland and Poland: Julia Holbein, Rochus Franke, Lukas Schreiber and Florian M. W. Grundler of the University of Bonn; Peter Marhavy, Satosha Fujita, and Niko Geldner of the University of Lasuanne, Switzerland; and Miroslawa Górecka and Miroslaw Sobeczak of the Warsaw University of Life Sciences, Poland.

“Plant-parasitic nematodes are among the most destructive plant pathogens, causing agricultural losses amounting to $80 billion annually in the United States,” said Siddique. “They invade the roots of almond, tomato, beets, potato or soybeans and migrate through different tissues to reach the central part—the vascular cylinder--of the root where they induce permanent feeding sites.”

“These feeding sites are full of sugars and amino acids and provide the parasite all the nutrients they need,” Siddique explained. “A specialized cell layer called the endodermis surrounds the vascular system and helps regulates the flow of water, ions and minerals into and out of it. However, the role of endodermis in protecting the vascular system against invaders such as nematodes had remained unknown.”

In their abstract, the scientists noted that plant-parasitic nematodes (PPN) “cause tremendous yield losses worldwide in almost all economically important crops. The agriculturally most important PPNs belong to a small group of root‐infecting sedentary endoparasites that includes cyst and root‐knot nematodes. Both cyst and root‐knot nematodes induce specialized long‐term feeding structures in root vasculature from which they obtain their nutrients.”

“A specialized cell layer in roots called the endodermis, which has cell walls reinforced with suberin deposits and a lignin‐based Casparian strip (CS), protects the vascular cylinder against abiotic and biotic threats,” the researchers explained. “Until now, the role of the endodermis, and especially of suberin and the CS, during plant–nematode interactions was largely unknown.”

The research was funded by a grant from the German Research Foundation.

(Note: The Plant Journal is a peer-reviewed scientific journal of plant science published by Wiley-Blackwell for the Society for Experimental Biology. Established in 1991, the journal is published twice a month. Editor Lee Sweetlove says that the journal "provides a dynamic forum for the ever-growing international plant sciences research community and publishes in all key areas of plant biology.")